The present disclosure relates to a mining machine and method whereby a mining machine can be operated to move across a seam containing minerals to be mined. The disclosure has particular, although not exclusive application, in the longwall mining of coal. Still more particularly, this disclosure relates to a mechanism and method to control the functions of a longwall miner in response to observations of the coal panel face alignment.
In the mining of coal, processes have been developed which are referred to as longwall mining processes. In these processes a movable rail is placed to span across a coal seam. A mining machine is provided with a shearing head or a plough and the mining machine is moved to traverse along the rail in one direction along the seam, and the shearing head or plough is manipulated upwardly and downwardly to shear coal from the face of the seam. Throughout each pass, the rail is moved forwardly toward the seam behind the path of the mining machine. The mining machine is then caused to traverse the seam in the opposite direction whilst the shearing head is manipulated upwardly and downwardly to remove further coal from the seam. The process is repeated until all coal in the planned extraction panel is completed. In order to protect the mining machine from falling material, a powered roof support is provided above the rail and the mining machine, and moves with the rail.
Coal is transferred from the seam by an armored face conveyor. Each section of the face conveyor is connected to the powered roof support by a double-acting hydraulic cylinder or ram. After the coal in front of a given face conveyor section is mined, its corresponding roof support is lowered and advanced and then hydraulically “set” against the roof, with the face conveyor section then being advanced. U.S. Pat. No. 4,228,508 illustrates such a longwall mining system. Thus, by advancing the rail means forwardly towards the seam by a suitable distance after each pass, it is possible to progressively move into the seam with an approximate equal depth of cut with each pass.
Proper maintenance of face alignment of the mining machine to the panel being cut is important in maximizing productivity in longwall coal mining. In other words, and as further illustrated in the drawings, it is important to make sure that the orientation of the shearing machine or plough is parallel to the mineral face being cut. Misalignment to the panel face can require additional cuts to again obtain the desired panel profile resulting in significant loss of productivity. A wide variety of intervening circumstances, such as operator error, buildup of floor debris, uneven floor or roof, and deteriorating performance of miner hydraulic components can cause such a misalignment.